Schedule 16 


June 25, 1920 


DEPARTMENT OF THE INTERIOR 

JOHN BARTON PAYNE, Secretary 

[J.s, BUREAU OF MINES 

11 

FREDERICK G. COTTRELL, Director 


PROCEDURE FOR ESTABLISHING A LIST OF PERMISSIBLE 
MULTIPLE-SHOT BLASTING MACHINES; CHARACTER 
OF TESTS, CONDITIONS UNDER WHICH THE 
MACHINES WILL BE TESTED, AND FEES 



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WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1921 


Collected set. 



The Bureau of Mines, in carrying out one of the provisions of its organic act—to 
disseminate information concerning investigations made—prints a limited free edition 
of each of its publications. 

When this edition is exhausted, copies may be obtained at cost price only through 
the Superintendent of Documents, Government Printing Office, Washington, D. C. 

The Superintendent of Documents is not an official of the Bureau of Mines . His is 
an entirely separate office, and he should he addressed: 

Superintendent of Documents, 

Government Printing Office, 

Washington, D. C. 

The general law under which publications are distributed prohibits the giving 
of more than one copy of a publication to one person. The price of this publication is 
5 cents. 

( 2 ) 


LIBRARY OF CONGRESS 

p t30EIVEQ 

APR 9-1921 

! documents division 

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PROCEDURE FOR ESTABLISHING A LIST OF PERMISSIBLE MULTIPLE- 
SHOT BLASTING MACHINES; CHARACTER OF TESTS, CONDITIONS 
UNDER WHICH THE MACHINES WILL BE TESTED, AND FEES. 


PRELIMINARY STATEMENT. 

AUTHORIZATION. 

An act of Congress (37 Stat., 681) approved February 25, 1913 r 
contains the following provision in regard to tests or investigations 
performed by the Bureau of Mines: 

That for tests or investigations authorized by the Secretary of the Interior under 
the provisions of this act, other than those performed for the Government of the United 
States or State governments within the United States, a reasonable fee covering the 
necessary expenses shall be charged according to a schedule prepared by the Director 
of the Bureau of Mines and approved by the Secretary of the Interior, who shall 
prescribe rules and regulations under which such tests or investigations may be made. 
All moneys received from such sources shall be paid into the Treasury to the credit 
of miscellaneous receipts. 

The term ‘‘multiple-shot blasting machine” refers to any hand- 
operated electrical device designed to fire two or more electric detona¬ 
tors or electric igniters at one time. 

In mining and quarry work many accidents occur through the use 
of improper means of shot-firing or the use of blasting machines of 
insufficient capacity. Therefore, the establishment of a list of per¬ 
missible apparatus that have been proved durable and reliable in 
operation and capable of delivering their rated capacity should tend 
to make shot-firing less dangerous. 

This schedule includes tests to determine the durability of parts 
and the reliability of operation, and to insure that the machine has 
its rated capacity. 

The Bureau of Mines is prepared at its Pittsburgh experiment 
station to conduct tests on multiple-shot blasting machines for use 
in quarries and nongaseous mines. This schedule of tests is issued 
for the information of those who may desire to submit equipment 
for test. 

DEFINITION OF “PERMISSIBLE.” 

The Bureau of Mines considers a multiple-shot blasting machine 
to be permissible for use in nongaseous mines and quarries if the 
details of the construction of said machine are the same in all respects 
as those of the machine that met the requirements and passed 
inspection and tests in accordance with this schedule. 

36064°—21 (3) 



4 


CONDITIONS UNDER WHICH MULTIPLE-SHOT BLASTING MACHINES 

WILL BE TESTED. 

The conditions under which the Bureau of Mines will examine 
and test multiple-shot blasting machines to establish their permissi¬ 
bility are as follows: 

1. The tests will be made at the experiment station of the Bureau 
of Mines at Pittsburgh, Pa. 

2. Applications for tests shall be addressed to the Director, Bureau 
of Mines, Washington, D. C., and shall be accompanied by a certified 
check or bank draft made payable to the Secretary of the Interior, to 
cover the total fees required for the desired tests, and by a complete 
description of the equipment to be tested and a full set of the drawings 
mentioned below: 

A drawing or drawings clearly showing the character, size, and 
relative arrangement of the complete blasting machine. The drawing 
or drawings shall specify the material of which all parts are made. 

A copy of the description, a duplicate set of the drawings, and one 
complete blasting machine shall be sent for preliminary examination 
to the electrical engineer, Bureau of Mines, 4800 Forbes Street, 
Pittsburgh, Pa. 

The description shall state the maximum resistance, in ohms, 
through which the machine will satisfactorily shoot electric detonators, 
connected in series. 

3. As soon as possible after receipt of his application for test the 
manufacturer will be notified of the date on which his equipment 
will be tested and the amount of any additional material that will be 
necessary for him to submit. 

4. The manufacturer shall deliver to the Bureau of Mines, 4800 
Forbes Street, Pittsburgh, Pa., two weeks prior to the date set for 
the test, the necessary material for determining the permissibility 
of his blasting machine. The tests will be made in the order of the 
receipt of applications for test, provided that the necessary material 
is submitted at the proper time. If the necessary material is not 
received at the date set for beginning test, the applicant next in line 
shall have precedence. 

5. No blasting machine will be tested unless it is in the completed 
form in which it is to be put on the market. 

6. No one is to be present at these tests except the necessary Gov¬ 
ernment officers, then 1 assistants, representatives of the manufacturer 
of the machine to be tested, and such other persons as may be mutu¬ 
ally agreed upon by the manufacturers and the bureau. 

7. The details of the results of the tests shall be regarded as confi¬ 
dential by all present at the tests and shall not be made public in 
any way prior to their official publication by the Bureau of Mines. 














5 


REQUIREMENTS FOR APPROVAL. 

The requirements that a multiple-shot blasting machine must have 
to pass successfully the inspection and tests required by the bureau 
are as follows: 

1. All parts shall be constructed of suitable material of the best 
quality and assembled in a substantial manner. 

2. All electrical contacts shall be so designed, installed, and pro¬ 
tected that their proper operation shall not be prevented by moisture 
or dust. 

3. Machines shall he so designed that there shall be no possibility 
of firing the external circuit until the plunger or equivalent mechanism 
shall have reached the end of its stroke. Machines designed to oper¬ 
ate within 0.02 of 1 second of the end of the stroke will be accepted 
as meeting this requirement. 

4. The rating of each blasting machine submitted for test will be 
determined by the bureau as 66§ per cent of the resistance in ohms, 
through which the machine will shoot two standard commercial elec¬ 
tric detonators (in series), the resistance of whose bridge wires differ 
by at least 20 per cent from each other. This determination shall 
be the average result of five trials by each of three operators. More 
trials will be made if, in the discretion of the bureau’s engineers, they 
are deemed necessary. 

5. Life test .—Two blasting machines will be operated 25,000 times 
each by a machine that approximates average hand operation of the 
given blasting machines. These 25,000 operations will be interrupted 
with periods of rest of such frequency and length as in the judgment 
of the bureau’s engineers will prevent any abnormal operating condi¬ 
tions being imposed upon the machine under test. 

6. At the end of the life test the machines under test shall be 
inspected and cleaned. Each machine shall then satisfactorily deliver 
its rated capacity. 

7. The excellence of the mechanical and electrical features of the 
design and construction of multiple-shot blasting machine will be 
considered with especial reference to the reliability of operation and 
durability of parts. 

8. The manufacturer shall furnish with each machine a compre¬ 
hensive table of resistances of detonator bridges, legs, leading wire, 
and connecting wire in commercial use, in order that the user of the 
machine may determine the approximate total resistance of that which 
makes up his firing circuit and from the approximation judge whether 
or not the number of shots in that circuit are within the rated capacity 
of the machine. The contents of this table of resistances shall meet 
with the approval of the bureau. 


6 


NOTIFICATION OF MANUFACTURER. 

As soon as the bureau’s engineers are satisfied that a blasting 
machine is permissible the manufacturer of the machine and the mine 
inspection departments of the several States shall be notified to that 
effect. As soon as the manufacturer receives formal notification that 
his machine has passed the tests prescribed by the bureau he shall be 
free to advertise such blasting machine as permissible. 

APPROVAL PLATES. 

The manufacturer will be required to attach to the casing of each 
permissible blasting machine a plate bearing the seal of the Bureau 
of Mines and inscribed as follows: 

Permissible Multiple-Shot Blasting Machine. 

Rating: .ohms. 

Approval No. 

Issued for capacity and for reliability and durability in general service in quarries 
and nongaseous mines to the.Company. 

For firing electric detonators or igniters in series when included in a circuit the- 
total resistance of which does not exceed.ohms. 

The approval plate shall include an appropriate caution statement 
calling attention to the necessity for the use of the resistance tables 
furnished with the machine in order that the total resistance of the 
firing circuit shall not be in excess of the rating of the machine. 

The size, material, and design of the approval plate shall be sub¬ 
ject to the approval of the bureau. The manufacturer will be fur¬ 
nished a photographic print of the wording and seal to be incor¬ 
porated in the approval plate design. 

A blasting machine will not be considered as permissible if used 
without the approval plate. 

SCOPE OF APPROVAL. 

The bureau’s approval of any blasting machine shall be construed 
as applying to all machines made by the same manufacturer that 
have the same construction in the details considered by the bureau, 
but to no other machines. 

Manufacturers shall, before claiming the bureau’s approval for 
any modification of any approved blasting machine, submit to the 
bureau drawings that show the extent and nature of such modifi¬ 
cations, in order that the bureau may decide whether or not it 
should test the remodeled machine before approving it. Each 
approval of a permissible blasting machine will be given a serial 
number. Approvals of modified forms of a previously approved 
machine will bear the same number as the original approval, with 
the addition of the letters, a, b, c, etc. 













7 


WITHDRAWAL OF APPROVAL. 

The bmeau reserves the right to rescind, for cause, at any time 
any approval granted under the conditions herein set forth. 

FEES. 

The following schedule of fees has been established and approved 
foi investigations of multiple-shot blasting machines: 

Fee for a complete investigation leading to the approval of a multiple-shot 

blasting machine. $150 

SEGREGATED CHARGES. 

Preliminary inspection. 10 

Records of physical and electrical characteristics. 20 

Life and capacity tests. 110 

Final inspection. 10 

150 

REMITTANCES. 

Manufacturers who submit multiple-shot blasting machines for 
tests to determine permissibility for use in quarries and nongaseous 
mines will be required to furnish with the application, a certified 
check or bank draft, made payable to the Secretary of the Interior, 
to cover the total fees required for the desired tests. 

SYNOPSIS OF PROCEDURE TO BE FOLLOWED IN MAKING APPLICA¬ 
TION FOR TESTS, SUBMITTING MATERIAL, CONDUCTING TESTS, 

AND NOTIFYING APPLICANT OF RESULTS. 

1. Application for tests should be addressed to the Director of 
the Bureau of Mines, Washington, D. C. This application should 
be accompanied by certified check or bank draft and by a complete 
description of the machine to be tested and a set of the drawings, 
described in paragraph 2, page 4. Duplicate copies of the appli¬ 
cation, description, and drawings should be sent to the electrical 
engineer, Bureau of Mines, 4800 Forbes Street, Pittsburgh, Pa., 
accompanied by a single complete blasting machine. 

2. As soon as the application has been reviewed by the bureau’s 
engineers the applicant will be notified of the date of test and the 
number of machines and the machine parts that it will be necessary 
for him to submit. 

3. After receiving this notification the applicant should send the 
material required to the electrical engineer, Bureau of Mines, 4800 
Forbes Street, Pittsburgh, Pa. This material should be delivered 
not less than two weeks in advance of the date set for the beginning 
of the tests. At this time the applicant should state the names 
and addresses of the applicant’s representatives who will witness 

the tests. 











8 


4. The tests will be begun on the date set and continued until 
the machine is approved, rejected, or withdrawn. 

5. After the bureau’s engineers have considered the results of the 
tests, a formal report of the approval or disapproval of the blasting 
machine will be made to the applicant in writing by the Director of 
the Bureau of Mines. No verbal report will be made and the details 
of the tests must be regarded as confidential by all present. 

Frederick G. Cottrell, 

Director . 

Approved June 25, 1920. 

John Barton Payne, 

Secretary. 

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